One neat feature of Udemy is the ability to download courses to your mobile device for "OFFLINE" viewing, using the Udemy mobile phone application. This works out well, except when your device is storage bound. This is particularly a problem for Apple iPhone users, but may apply to certain Android users as well.
The next best option is to download to your notebook (yes, for desktops as well but they are not that portable to take with you on the go). However, Udemy courses are not downloadable from the web interface, unless the instructor specifically allowed the download. Is it still possible? HOW?!

Yes, it is possible. You are as interested in doing it as I am. And here's how.

First, install Python on your notebook. If you don't have it yet, download miniconda3 (link: https://conda.io/miniconda.html). When installing miniconda3, make sure to include python on your PATH.

Next, clone or download the zip of the udemy-dl github repository (link: https://github.com/r0oth3x49/udemy-dl). Expand the zip file to a directory of your choice. Open the requirements.txt file. Use conda to install the libraries listed. Or if you want simply, run "pip install -r requirements.txt". The use of conda is recommended, but as I have tested pip also works. Either way, it installs the modules or libraries required.

You are now ready to download the Udemy course of your choice. Note and copy the URL of your course.

Then execute "python udemy-dl.py http://www.udemy.com/replace-this-link-with-the-course-url/". Do not forget to replace the http URL with the course URL.